{"id":2426,"date":"2023-02-06T08:00:18","date_gmt":"2023-02-06T08:00:18","guid":{"rendered":"http:\/\/admin.acceleratingscience.com\/?p=2426"},"modified":"2026-03-03T22:27:07","modified_gmt":"2026-03-03T22:27:07","slug":"pyrite-the-real-story-behind-fools-gold","status":"publish","type":"post","link":"https:\/\/www.thermofisher.com\/blog\/mining\/pyrite-the-real-story-behind-fools-gold\/","title":{"rendered":"Pyrite: The Real Story Behind \u201cFool\u2019s Gold\u201d"},"content":{"rendered":"

Pyrite, often called \u201cFool\u2019s Gold,\u201d has captivated prospectors and geologists for centuries. But beyond its deceptive shine lies a mineral with real scientific and industrial significance.<\/strong><\/p>\n

\u201cFool\u2019s Gold\u201d is technically known as pyrite or iron sulfide (FeS2<\/sub>) and is one of the most common sulfide minerals<\/a>. Sulfide minerals are a group of inorganic compounds containing sulfur and one or more elements. Minerals are defined by their chemistry and crystalline structure. Minerals that have the same chemical composition but different crystal structures are called polymorphs.<\/p>\n

Pyrite and marcasite, for example, are polymorphs because they are both iron sulfide, but each has a distinct structure.\u00a0Minerals can also have the same crystalline structure but different elemental compositions, but it\u2019s the crystal structure that determines the mineral\u2019s physical characteristics.<\/p>\n

In addition to pyrite, common sulfides are chalcopyrite (copper iron sulfide), pentlandite (nickel iron sulfide), and galena (lead sulfide). The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, and the sulfosalts. Many\u00a0sulfides\u00a0are economically important as metal ores.<\/p>\n

Why is Pyrite called “Fool’s Gold”?<\/h2>\n

Pyrite is called \u201cFool\u2019s Gold\u201d because it resembles gold to the untrained eye.\u00a0The United States Geological Survey<\/a> (USGS) explains that “Fool’s Gold can be one of three minerals. The most common mineral mistaken for gold is pyrite. Chalcopyrite may also appear gold-like, and weathered mica can mimic gold as well. Compared to actual gold, these minerals will flake, powder, or crumble when poked with a metal point, whereas gold will gouge or indent like soft lead. In addition, actual gold will leave a golden yellow streak when scraped on a piece of unglazed porcelain. Pyrite and chalcopyrite will leave a dark green to black streak and the common micas will leave a white streak.” If you want to know more about how to tell real gold from \u201cFool\u2019s Gold,\u201d* watch this video<\/a> produced by the University of Knottingham.<\/p>\n

Pyrite is so named from the Greek word for fire (pyr) because it can create sparks for starting a fire when struck against metal or stone. This property made it useful for firearms at one time but this application is now obsolete. Pyrite was once a source of sulfur and sulfuric acid, but today most sulfur is obtained as a byproduct of natural gas and crude oil processing.<\/p>\n

Where Pyrite is Used<\/h2>\n

Today pyrite is sometimes sold as a novelty item or costume jewelry. But pyrite isn\u2019t entirely useless; in fact it\u2019s a good way to find real gold because the two form together under similar conditions. Gold can even occur as inclusions inside pyrite, sometimes in mineable quantities depending on how effectively the gold can be recovered.<\/p>\n

Pyrite has long been investigated for its semiconductor properties. The American Chemical Society<\/a> published a review on trends and challenges of iron pyrite in photovoltaics.\u00a0 The abstract notes; “Solar cells consisting of different materials have been introduced in recent years, and the overall performance defined by these materials has a lot of potential to increase. Transition metal dichalcogenides have gained significant importance due to their advantageous properties and promising potential. Iron disulfide or pyrite is one such material that has risen as a favorable material for photovoltaics cells owing to its suitable band gap, high absorption coefficient, and low cost.”*<\/p>\n

Where Pyrite is Found<\/h2>\n

Pyrite is found in a wide variety of geological settings, from igneous, sedimentary and metamorphic rock to hydrothermal mineral deposits, as well as in\u00a0coal\u00a0beds and as a replacement mineral in\u00a0fossils. Pyrite can be either disseminated throughout igneous rock or concentrated in layers, depending on depositional mechanism and environment. Pyrite forms in sedimentary rocks in oxygen-poor environments in the presence of iron and sulfur. These are usually organic environments, such as coal and black\u00a0shale, where decaying organic material consumes oxygen and releases sulfur. Pyrite often replaces plant debris and shells to create pyrite fossils or flattened discs called pyrite dollars.<\/p>\n

In calcite and quartz veins, pyrite oxidizes to iron oxides or hydroxides such as limonite, an indicator that there is pyrite in the underlying rock. Such oxidized zones are called \u201cgossan,\u201d which appears as rusty zones at the surface. Gossans can be a good drilling targets for gold and other precious or base metals.<\/p>\n

Pyrite is unstable and oxidizes easily, which is an issue in controlling acid mine drainage. Pyrite is a widespread natural source of arsenic, which can leach into ground-water aquifers when geologic strata containing pyrite are exposed to the air and water, during coal mining for example. Acid mine drainage and groundwater contamination requires close monitoring to ensure that it has been neutralized before being returned to the earth.<\/p>\n

Technology to Help Identify Pyrite<\/h2>\n

A question: If you have a shiny and tiny golden color spot in your sample, how would you identify it? Is it gold? Is it pyrite?\u00a0 Portable x-ray fluorescence (XRF) analyzers <\/a>are an important tool in this effort. In just a few seconds, you can identify that ‘rock’. \u00a0X-ray fluorescence spectroscopy (XRF)<\/a> is a non-destructive analytical technique used to determine the elemental composition of materials. XRF analyzers work by measuring the fluorescent (or secondary) X-rays emitted from a sample when excited by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic fluorescent X-rays, or \u201cunique fingerprints.\u201d These fingerprints are distinct for each element, making XRF analysis an excellent tool for quantitative and qualitative measurements.\u00a0 is a non-destructive analytical technique used to determine the elemental composition of materials.*<\/p>\n

At the exploration stage, a quick, non-destructive analysis is often required for outcrop and soil analysis, advanced exploration and drilling, core sample analysis, mine mapping, grade control, and cuttings analysis for mud logging and reservoir characterization. This data can enable geologists and miners to make data driven decisions on locations & sites… helping them to not be fooled by this fake gold.*<\/p>\n

Summary<\/h2>\n

Pyrite\u2014commonly known as \u201cFool\u2019s Gold\u201d\u2014is a widespread iron sulfide (FeS\u2082) mineral that often fools the untrained eye due to its metallic luster and brassy-yellow color. While it resembles gold, pyrite is chemically and physically distinct and will flake or crumble rather than bend like real gold. Historically used as a source of sulfur and for making sparks, today it\u2019s mainly a curiosity or jewelry item, though it can indicate the presence of real gold since the two minerals often form together. Pyrite also has potential in semiconductor and photovoltaic research, and understanding its properties helps geologists and miners make informed decisions in exploration and analysis.<\/p>\n

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Additional Resources<\/h2>\n